Rotary compressor

ABSTRACT

A VANE-TYPE ROTARY COMPRESSOR IS HOUSED IN A CYLINDRICAL CUP-SHAPED SHEET METAL HOUSING SHELL, THE COMPRESSOR ASSEMBLY COMPRISING THREE MAIN BODY SECTIONS OF GENERALLY CYLINDRICAL FOR INCLUDING A CYLINDRICAL STATOR SECTION SANDWICHED BETWEEN INNER AND OUTER COVERING SECTIONS SEALED IN THE SHELL AND ONE FORMING AN OUTER END CLOSURE WHICH DEFINES A BEARING SUPPORT, A SEAL CHAMBER, AND A SUPPORT FOR A DRIVING CLUTCH AND PULLEY, THE INTERNAL COVER SECTION BEING SPACED FROM THE CLOSED REAR WALL OF THE SHELL AND ACTING AS A REAR BEARING SUPPORT AND ALSO AS A PARTITION FOR A COMBINED OIL SUMP AND HIGH PRESSURE DISCHARGE CHAMBER AND ALSO SUPPORTING THE LUBRICANT FEEDING AND CONTROL MEANS AND THE SUCTION AND DISCHARGE CONDUITS. THE LUBRICATING MEANS COMPRISES A CAPILLARY TUBE FOR FEEDING OIL FROM THE SUMP AND A CENTRIFUGALLY OPERABLE VALVE WHICH CLOSES OFF ESCAPE OF OIL FROM THE SUMP WHEN THE COMPRESSOR IS NOT RUNNING. THE VANES ARE PROVIDED WITH VENT CHANNELS TO THE VANE POCKETS. A SECTION OF THE STATOR WALL WHICH IS ENGAGED BY THE VANES IN THE AREA DEFINING THE SEAL BETWEEN THE HIGH AND LOW PRESSURE REGIONS IS CONCENTRIC AND HAS A CLOSE FIT WITH THE ROTOR, TO PROVIDE A SEAL OF SUBSTANTIAL ANGULAR EXTENT AS DISTINGUISHED FROM A TANGENT SEAL BETWEEN THE ROTOR AND STATOR.

Feb. 2, 1971 W Y ETAL 3,560,120 RQTARY COMPRESSOR v l Original FiledMarch 18, 1962 .2 Sheets-Sheet 1 E. L. GANNAWAY ETAL Feb. 2, 1971 ROTARYCOMPRESSOR Original Filed March 18, 1962 -BY faizrff/fiw z O '/W%? 2Sheets-Sheet 2 INVENTORS J20! United States Patent Oflice 3,560,120Patented Feb. 2, 1971 3,560,120 ROTARY COMPRESSOR Edwin L. Gannaway andRobert M. Draper, Sidney, Ohio,

assignors to Copeland Refrigeration Corporation, Sidney, Ohio, acorporation of Michigan Continuation of application Ser. No. 713,581,Mar. 18, 1968. This application Sept. 9, 1968, Ser. No. 767,030 Int. Cl.F04c 29/02; F04d 29/06 U.S. Cl. 41884 4 Claims ABSTRACT OF THEDISCLOSURE A vane-type rotary compressor is housed in a cylindricalcup-shaped sheet metal housing shell, the compressor assembly comprisingthree main body sections of generally cylindrical form including acylindrical stator section sandwiched between inner and outer coveringsections sealed in the shell and one forming an outer end closure whichdefines a bearing support, a seal chamber, and a support for a drivingclutch and pulley, the internal cover section being spaced from theclosed rear wall of the shell and acting as a rear bearing support andalso as a partition for a combined oil sump and high pressure dischargechamber and also supporting the lubricant feeding and control means andthe suction and discharge conduits. The lubricating means comprises acapillary tube for feeding oil from the sump and a centrifugallyoperable valve which closes off escape of oil from the sump when thecompressor is not running. The vanes are provided with vent channels tothe vane pockets. A section of the stator wall which is engaged by thevanes in the area defining the seal between the high and low pressureregions is concentric and has a close fit with the rotor, to provide aseal of substantial angular extent as distinguished from a tangent sealbetween the rotor and stator.

The present application is a continuation of my previously filedco-pending application Ser. No. 713,581, filed Mar. 18, 1968, nowabandoned.

BACKGROUND OF THE INVENTION The present invention relates tocompressors, particularly for refrigeration service.

Important objects of the invention are the provision of improvedlubricating means for refrigerant compressors, an improved contouringand inter relationship between the rotor and stator portions ofvane-type compressors, whereby improved sealing and improved flowcharacteristics are attained, improved means for preventing unwantedmigration of lubricant during 01f cycles of the compressor, an improvedoverall arrangement and method of assembly of the components ofvane-type compressors, an improved external clutch-type drive mechanism,and improved arrangements of the bearing, component mounting means, andvane components thereof.

Other objects and advantages will be apparent upon consideration of thepresent disclosure in its entirety.

DETAILED DESCRIPTION OF A PREFERRED FORM OF THE INVENTION FIG. 1 is adiametric longitudinal sectional view of a compressor constructed inaccordance with the present invention, and

FIGS. 2 and 3 are cross-sectional views taken substantially on the linesII-II and III-III respectively, and looking in the direction of thearrows.

Referring now to the drawing, reference character designates generally asheet metal shell of cylindrical cross section closed at its rear end byan integral wall 11 and at its other end open to receive the mechanicalcomponents of the compressor, which are installed by sliding thecompleted assembly of compressor components into the casing to theposition shown,

The main components of the compressor assembly comprise the cylinderbody 12, the front cover section 14 and the rear cover section 15. Thecover sections are secured in the cylinder body by through bolts 16 andthe entire assembly is secured in the shell by radial screws 18 whichextend intosuitably tapped holes in the cover 14 through holes in theshell.

The body 12 has a substantially cylindrical pumping chamber 20 thereinof substantially greater diameter than the cylindrical pumping rotor 22and axially offset therefrom in the usual manner. The Wall of chamber 20is not strictly cylindrical, however, a portion 21 thereof r in thesealing region being concentric with and closely fitted to rotor 22throughout a portion (e.g. 45) of the periphery of the latter, that is,approximately from the position X to the position Y as designated inFIG. 2. The axis of rotation of the rotor is centered with respect tothe shell while the cylinder and chamber 20 are offset therefrom. Theextended sealing portion 21 provides an increased leakage barrier andprovides more clearance and reduced gas velocities in the part of thecompression chamber near the discharge ports 32.

The rotor is provided with four slidable vanes 25 arranged in non-radialslots 26. The slots and vanes are slanted to incline the vanes forwardlyin the direction of rotation, lying tangent to a circle whose radius isapproximately three-fifths that of the rotor. A pressure equalizingchannel 27 connects the bottom of the vane slot with the cylinder on thetrailing side of each of the vanes. Although this could be formed in theslot wall, it is more convenient to form it on the vane, as shown,extending the full distance between its inner and outer edges. When thevane is in the compression area the high pressure is thus able to actunder the vane to assist in maintaining vane contact, while when thevane moves into the low pressure area the high pressure under the vaneis vented through the channel, reducing load and wear. The channel alsopermits quick vane projection upon starting and elimintaes bouncing ofthe vanes.

As shown in FIG. 2, the cylinder body 12 does not fill the internalcross section of the shell. The suction line 28 which is the inlet tothe compressor extends through and in sealed relation to the rear wall11 and is connected to inlet chamber 30 in cover 15 to deliver suctiongas to the vane space, wherein it is compressed in the usual mannerbetween the vanes and the converging walls of the stator and rotor, anddischarged under pressure through the outlet valves 33 and ports 32 andinto chamber 35 lying outside the body 12. Compressed gas passes fromchamber 35 through holes 36 in cover 15 into the pressure chamber 38,the bottom of which also constitutes the oil sump.

The rotor 22 is keyed to shaft 40 which is journaled in antifrictionbearings 42, 44 in the front and rear covers 1 1, 15, respectively, andprojects forwardly to an exposed end to which a hub 60 is secured by atapered key and nut fastening 62. A flange disc 58 on hub 60 is drivableby an electromagnetically clutchable and declutchable pulley 45 to drivethe shaft and rotor. A neck 46 secured to and forming an axial extensionof front cover 14 supports the antifriction pulley bearing 50 upon whichthe pulley is freely rotatable and also supports an electromagnetassembly comprising the annular winding 52 so designed that itsprincipal effective lines of force are directed forwardly through theslotted web portion 54 of the pulley to act upon an axially displaceableannular plate-type armature 55 which is keyed to rotate with the shaftand which when drawn rearwardly by energization of the winding 52frictionally engages web 54 and so transmits the pulley drive to theshaft and rotor. The

armature 55 is supported for axial movement and held fast rotativelywith respect to the shaft, and also biased to the disengaged position,by the strap-type springs 56, each such spring being secured at itsouter end to the armature and at its inner end to hub flange 58.

The front cover 14 is formed with a forwardly opening axial seal chamber66 surrounding the shaft and which is closed by front support 46. Frontsupport 46 is attached to neck 64 by screws 48 which also secure andclamp the Supporting flange 53 for the coil of the electromagnet betweenparts 64-46. The grooved portion 47 of the pulley overhangs the coil andis aligned with hearing 50 which is in turn supported by the fixedhousing portion 46. Thus the entire belt load is taken by the housingand is transmitted in straight compression through the bearing and nolateral loads are imposed on the shaft. In addition if the unit isinstalled in a situation which subjects it to vibration, as in a motorvehicle, the bearing 50 will 1'0- tate constantly, thereby reducing thetendency to workharden and fret the balls and contacting race areas ofthe bearing.

The seal assembly, generally designated 70, may be of conventionalconstruction and detailed description thereof will not be required. Itsrotary sealing ring 68, which is sealed with respect to the shaft, has aseal-defining running fit against fixed ring 69 which is in turn sealedagainst the inner peripheral wall of chamber 66.

The high pressure outlet chamber 38 contains an oil feed and controlassembly the body 75 of which is secured by screws 74 to the rear faceof cover 15. Means is provided for metering oil from the sump tolubricated components at a relatively constant rate when the compressoris running, the flow being motivated by the discharge pressure inchamber 38. Although other known means might be used, our preferredconstruction incorporates a capillary feed tube 78 having an open lowerend submerged in the oil in the sump. The oil which is forced throughthe tube is carried via a passage 82 to a valve chamber 84 from whichits escape is blocked by a ball valve 85 when the compressor is not inoperation. When the compressor is operating at normal speed, the valveis opened by centrifugal force developed by flyweight 86. As shown inFIG. 1, the capillary tube 78 is coiled in a chamber 76 defined by adepending open-bottomed tubular portion of body 75 and the lower end ofwhich is protected by a screen 77, the upper end of chamber 76 beingclosed by a partition 80 through which the upper end of capillary tube78 projects into communication with passage 82. Valve ball 85 is urgedby Spring 88 against its seat 90. Flyweight 86 is pivotally mounted on apin 92 carried by a rotary disc 104 carried by the rear end of shaft 40.The flyweight moves radially in a plane transverse to the axis in achamber 94 which encloses the disc and the flyweight is urged radiallyinward by a hairpin spring 95 and outwardly by centrifugal force whenthe compressor is in operation. A cam portion 96 integral with theflyweight reacts against an axially slidable follower pin 98 as theflyweight moves outwardly, to unseat the ball 85, while when the shaftis at rest and the flyweight drawn inwardly against stop pin 97 byspring 95, the follower pin 100 and ball 85 are permitted to move to thevalve-closed position under the influence of the spring 88.

When valve 85 is open, fluid is forced via chamber 84, passage 100 andchamber 94 to a passage 102 drilled axially through the disc- 104.Housing 75 is sealed against the rear face of cover 15 in the areasurrounding chamber 94 and an axial passage 105 drilled in the shaft 40from the rear end thereof forms a continuation of passage 102 in disc104. Passage 105 feeds oil through suitable communicating passages andports as 106, 107, 108, 109 to the seal chamber 65 and to other workingparts as shown. All of the pressure drop occurs in capillary tube 78 sothat the oil is at low pressure as it enters the seal area and otherworking parts. This is of advantage from the standpoint of seal life.

When the compressor is used in a refrigeration system, it is normal forsome refrigerant in liquid form to be contained with the oil in the sumpdue to the high pressure in the discharge chamber. As the oil which isthus charged with a certain amount of refrigerant leaves the capillarytube and the high pressure area and enters the lubricant passages 105,etc., which are in low pressure zones, the refrigerant contained in theoil vaporizes and expands, thereby giving a cooling effect on the seal,bearing and other lubricated components.

The oil is only able to return to the sump by escaping past the workingsurfaces and passing through outlet ports 32, chamber 35 and openings 36to chamber 38, which acts as an oil separator due to the reduction ofvelocity and change of direction of the oil-carrying gas entering suchchamber. When the compressor stops, closure of the valve preventsmigration of oil into the working areas of the compressor under thepressure remaining in chamber 38. Noise and possible damage to thevalves and other parts which might be caused by excess oil on subsequentstartup are thereby prevented.

This Detailed Description of a Preferred Form of the Invention, and theaccompanying drawings, have been furnished in compliance with thestatutory requirement to set forth the best mode contemplated by theinventors of carrying out the invention. The prior portions consistingof the Abstract of the Disclosure and the Background of the Inventionare furnished without prejudice in an elfort to comply withadministrative requirements of the patent What is claimed is:

1. In a compressor having working parts which require lubrication andhaving an oil sump pressurized by the output, means for delivering acontrolled supply of lubricant to the working parts including passagemeans, flow limiting means for connecting said passage means to thesump, a valve closable to interrupt flow through said pas sage meansfrom the sump, and means including a centrif ugal actuator for openingsaid valve in response to operation of the compressor and formaintaining the valve in closed position when the compressor is notoperating.

2. A compressor as defined in claim 1 wherein said flow limiting meansis a capillary tube.

3. A compressor as defined in claim 1 of the type having an accessibleshaft drivable by an external power source, rotary sealing parts forpreventing leakage along the shaft, and a lubricant chamber surroundingsaid sealing parts and fed from said passage means, said flow limitingmeans providing when the valve is open a supply of lubricant to saidchamber at a pressure lower than that prevailing in the sump.

4. In a refrigerant compressor having a low pressure zone containingworking parts which require lubrication and having a high pressure zoneincluding an oil sump connected to and pressurized by the output of thecompressor, means for lubricating and cooling the working partscomprising oil feeding means connecting said sump to such working parts,combined oil conducting and pres sure reducing regulating meansincluding a capillary tube forming a part of said feeding means and alsoacting as the pressure reducing regulating means and having a uniformdiameter which is small in proportion to its length, said tube havingits inlet end in said sump and its outlet end connected to the workingparts in the low pressure zone.

References Cited UNITED STATES PATENTS 1,558,620 10/ 1925 Kagi 2310-207X2,496,676 2/1950 IRawson 230-207 3,243,103 3/1966 Bellmer 230207 ROBERT-M. WALKER, Primary Examiner US. Cl. XIR.

